Driving support apparatus

ABSTRACT

A driving support apparatus according to the invention estimates the position of a moving body by controlling a position estimation unit when the tracking-target moving body leaves a first area or a second area to enter a blind spot area and detects the position of the moving body by controlling a position detection unit when the moving body leaves the blind spot area to enter the first area or the second area. In this manner, the trajectory of the tracking-target moving body is calculated so that the trajectory of the moving body detected in the first area or the second area and the trajectory of the moving body estimated in the blind spot area are continuous to each other and driving support is executed based on the calculated trajectory of the tracking-target moving body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 16/881,420, filed May 22, 2020, which is acontinuation of U.S. application Ser. No. 16/124,412, filed Sep. 7,2018, which is now U.S. Pat. No. 10,696,297, issued Jun. 30, 2020, whichis a continuation of U.S. application Ser. No. 15/312,698, filed Nov.21, 2016, which is now U.S. Pat. No. 10,106,154, issued Oct. 23, 2018,which is a National Stage of International Application No.PCT/IB2015/000751, filed May 27, 2015, which is based upon and claimsthe benefit of priority from Japanese Patent Application No.2014-111774, filed May 29, 2014. The benefit of priority is claimed toeach of the foregoing, and the entire contents of each of the foregoingare incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a driving support apparatus.

2. Description of Related Art

Techniques have been reported for detecting information on the positionof another moving body that is present on a lateral side of a subjectvehicle by using a plurality of sensors. For example, Japanese PatentApplication Publication No. 2010-211504 (JP 2010-211504 A), discloses anobject detection apparatus that is capable of detecting the position ofa vehicle traveling in the vicinity of a roadside object. In addition,Japanese Patent Application Publication No. 2012-159348 (JP 2012-159348A) discloses a technique in which a side detection target is registeredas a tracking target that needs to be tracked in a side detection areawhen a moving target is detected in an overlapping area based on theresult of measurement in a rear search mode and information on theoverlapping-area moving target is handed over to the registered trackingtarget.

In a case where driving support for another moving body traveling inparallel to the vehicle by the vehicle is executed, the trajectory ofthe moving body has to be checked with accuracy from the position of thetracking-target moving body detected between the plurality of sensorsmounted on the subject vehicle.

According to the related art, however, the trajectory of the moving bodymay not be checked in a case where the other moving body traveling inparallel to the vehicle by the vehicle moves into a blind spot areabetween the plurality of sensors. In this case, the trajectory of themoving body cannot be checked once the moving body enters the blind spotarea, although the driving support can continue, in a state where thetrajectory of the tracking-target moving body can be checked in theareas detected by the sensors, and thus an event occurs in which thedriving support that should be continuously executed is halted. Inaddition, the halted driving support may be abruptly resumed once themoving body in the blind spot area moves back into the detected area. Inthis case, a driver may feel uncomfortable.

According to the related art as described above, the trajectory of thetracking-target moving body cannot be calculated when the moving bodymoves into the blind spot area from within the area detected by thesensor during the execution of the driving support for thetracking-target moving body. Accordingly, driving support for avoiding,for example, a collision with the moving body may not be performed withcontinuity.

SUMMARY OF THE INVENTION

The invention provides a driving support apparatus that can continuouslyexecute the driving support based on the trajectory of the moving bodytracked by checking the position of the moving body moving in the blindspot area even in a case where another moving body traveling in parallelto a vehicle by the vehicle moves into a blind spot area between aplurality of sensors during the execution of the driving support for thetracking-target moving body.

The driving support apparatus according to the invention includes afirst sensor provided at a front lateral side mounting position of asubject vehicle and detecting a situation of a first area on a frontlateral side of the subject vehicle, a second sensor provided at a rearlateral side mounting position of the subject vehicle and detecting asituation of a second area on a rear lateral side of the subjectvehicle, the second area being an area different from the first area, aposition detection unit configured to detect the position of atracking-target moving body moving in the first area and the secondarea, a position estimation unit configured to estimate the position ofthe tracking-target moving body moving in a blind spot area based on theposition of the tracking-target moving body detected in any one of thefirst area and the second area by the position detection unit, the blindspot area being a surrounding area on a lateral side of the subjectvehicle and being an area other than the first area and the second area,a trajectory calculation unit configured to calculate the trajectory ofthe tracking-target moving body, so that the trajectory of the movingbody detected in the first area and the second area and the trajectoryof the moving body estimated in the blind spot area are continuous toeach other, by estimating the position of the moving body by controllingthe position estimation unit when the tracking-target moving body leavesone of the first area and the second area and enters the blind spot areaand by detecting the position of the moving body by controlling theposition detection unit when the moving body leaves the blind spot areaand enters the other one of the first area and the second area, and asupport execution unit configured to execute driving support based onthe trajectory of the tracking-target moving body calculated by thetrajectory calculation unit.

In the driving support apparatus, the support execution unit may beconfigured to change a content of the support for the driving support inaccordance with estimation accuracy of the position of thetracking-target moving body estimated by the position estimation unit.

In the driving support apparatus, the support execution unit may beconfigured to execute the driving support by executing vehicle controlin a case where the estimation accuracy is high and may be configured toexecute the driving support by providing notification in a case wherethe estimation accuracy is low.

In the driving support apparatus, the estimation accuracy may be set todecrease as a relative speed between the subject vehicle and thetracking-target moving body decreases and to increase as the relativespeed increases.

In the driving support apparatus, the estimation accuracy may be set inaccordance with an attribute of the tracking-target moving body.

In the driving support apparatus, the estimation accuracy may be set toincrease as an acceleration and deceleration of the moving body otherthan the tracking-target moving body present around the subject vehicleat which the moving body approaches the tracking-target moving bodydecreases and to decrease as the acceleration and decelerationincreases.

In the driving support apparatus, the estimation accuracy may be set toincrease as a distance from the subject vehicle to an intersectionincreases and to decrease as the distance decreases.

In the driving support apparatus, the estimation accuracy may be set toincrease as a humidity around the subject vehicle decreases and todecrease as the humidity increases.

In the driving support apparatus, the estimation accuracy may be set toincrease as a rainfall around the subject vehicle decreases and todecrease as the rainfall increases.

According to the driving support apparatus of the invention, the drivingsupport can be continuously executed based on the trajectory of themoving body tracked by checking the position of the moving body movingin the blind spot area even in a case where the other moving bodytraveling in parallel to the vehicle by the vehicle moves into the blindspot area between the plurality of sensors during the execution of thedriving support for the tracking-target moving body.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a diagram illustrating the configuration of a driving supportapparatus according to the invention;

FIG. 2 is a diagram illustrating examples of areas detected by aplurality of surrounding environment recognition sensors mounted on avehicle and a blind spot area;

FIG. 3 is a diagram illustrating an example of a situation in which atrajectory of a tracking-target moving body passing through the blindspot area is calculated;

FIG. 4 is a diagram illustrating an example of a situation in whichestimation accuracy is set in accordance with a relative speed;

FIG. 5 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and the relative speed;

FIG. 6 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and an attribute;

FIG. 7 is a diagram illustrating an example of a situation in which theestimation accuracy is set in accordance with the acceleration anddeceleration of moving body;

FIG. 8 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and the acceleration and deceleration;

FIG. 9 is a diagram illustrating an example of a situation in which theestimation accuracy is set in accordance with the distance to anintersection;

FIG. 10 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and the intersection;

FIG. 11 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and humidity;

FIG. 12 is a diagram illustrating an example of a relationship betweenthe estimation accuracy and a wiper operation speed;

FIG. 13 is a flowchart illustrating an example of the basic processingthat is executed by the driving support apparatus according to theinvention; and

FIG. 14 is a flowchart illustrating examples of estimation accuracysetting processing and driving support change processing that areexecuted by the driving support apparatus according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a driving support apparatus according tothe invention will be described in detail with reference to theaccompanying drawings. The invention is not limited to the embodiment.The components of the embodiment described below include those that canbe readily assumed by those skilled in the art or those substantiallyidentical thereto.

[Embodiment] The configuration of the driving support apparatusaccording to the invention will be described with reference to FIGS. 1to 12 . FIG. 1 is a diagram illustrating the configuration of thedriving support apparatus according to the invention. FIG. 2 is adiagram illustrating examples of areas detected by a plurality ofsurrounding environment recognition sensors mounted on a vehicle and ablind spot area. FIG. 3 is a diagram illustrating an example of asituation in which a trajectory of a tracking-target moving body passingthrough the blind spot area is calculated. FIG. 4 is a diagramillustrating an example of a situation in which estimation accuracy isset in accordance with a relative speed. FIG. 5 is a diagramillustrating an example of a relationship between the estimationaccuracy and the relative speed. FIG. 6 is a diagram illustrating anexample of a relationship between the estimation accuracy and anattribute. FIG. 7 is a diagram illustrating an example of a situation inwhich the estimation accuracy is set in accordance with the accelerationand deceleration of moving body other than the following vehicle. FIG. 8is a diagram illustrating an example of a relationship between theestimation accuracy and the acceleration and deceleration. FIG. 9 is adiagram illustrating an example of a situation in which the estimationaccuracy is set in accordance with the distance to an intersection. FIG.10 is a diagram illustrating an example of a relationship between theestimation accuracy and the intersection. FIG. 11 is a diagramillustrating an example of a relationship between the estimationaccuracy and humidity. FIG. 12 is a diagram illustrating an example of arelationship between the estimation accuracy and a wiper operationspeed.

In this embodiment, an ECU 1 functions as the driving support apparatusfor executing driving support based on the trajectory of the moving bodythat is tracked by detecting or estimating the position of the movingbody traveling in parallel to a subject vehicle by the subject vehiclefrom information which is input from surrounding environment recognitionsensors 3. The ECU 1 is electrically connected to vehicle momentumdetection sensors 2, the surrounding environment recognition sensors 3,a navigation system 4, a humidity sensor 5, a wiper sensor 6, anactuator 7, a display 8, and a speaker 9. The ECU 1 performs computationprocessing based on various signals that are input from the vehiclemomentum detection sensors 2, the surrounding environment recognitionsensors 3, the navigation system 4, the humidity sensor 5, and the wipersensor 6. The ECU 1 executes the driving support via at least one of theactuator 7, the display 8, and the speaker 9 in accordance with theresult of the computation processing based on the various signals.

The vehicle momentum detection sensors 2 are vehicle momentum detectiondevices that detect various types of information showing a vehiclemomentum. In this embodiment, the vehicle momentum detection sensors 2include an acceleration sensor 2 a, a yaw rate sensor 2 b, and a vehiclespeed sensor 2 c. The acceleration sensor 2 a is an accelerationdetection device that detects an acceleration which is applied to avehicle body. The acceleration sensor 2 a outputs, to the ECU 1, asignal that shows the magnitude of the detected acceleration. The yawrate sensor 2 b is a yaw rate detection device that detects the yaw rateof the vehicle. The yaw rate sensor 2 b outputs, to the ECU 1, a signalthat shows the magnitude of the detected yaw rate. The vehicle speedsensor 2 c is a vehicle wheel speed detection device that is disposed ineach vehicle wheel and detects each vehicle wheel speed. The vehiclespeed sensor 2 c detects the vehicle wheel speed that is the rotationspeed of each vehicle wheel. The vehicle speed sensors 2 c output, tothe ECU 1, signals that show the detected vehicle wheel speeds of therespective vehicle wheels. The ECU 1 calculates the vehicle speed thatis the traveling speed of the vehicle based on the vehicle wheel speedsof the respective vehicle wheels input from the respective vehicle speedsensors 2 c. The ECU 1 may calculate the vehicle speed based on thevehicle wheel speed that is input from at least one of the vehicle speedsensors 2 c. As described above, the vehicle momentum detection sensors2 detect the acceleration that is detected by the acceleration sensor 2a, the yaw rate that is detected by the yaw rate sensor 2 b, and thevehicle wheel speed that is detected by the vehicle speed sensor 2 c asthe information showing the vehicle momentum, and output the informationto the ECU 1.

The surrounding environment recognition sensors 3 are surroundingenvironment recognition devices that recognize a situation surroundingthe vehicle such as a moving object and a stationary obstacle around thevehicle. Radar, a camera, and the like constitute the surroundingenvironment recognition sensors 3. The surrounding environmentrecognition sensors 3 acquire, as surrounding environment information,information such as a relative position of a white line on a road, arelative position of a surrounding obstacle, and a relative position, arelative speed, and a relative acceleration with respect to asurrounding moving target, and output the surrounding environmentinformation to the ECU 1. In addition, the surrounding environmentrecognition sensors 3 may acquire, as the surrounding environmentinformation, information relating to the attribute of the surroundingobstacle such as the strength, brightness, and color of the recognitiontarget as well as the information such as the relative position and therelative speed of the recognition target around the vehicle and mayoutput the surrounding environment information to the ECU 1. Forexample, in a case where the radar constitutes the surroundingenvironment recognition sensors 3, the wavelength patterns of thereflected waves of the radar differ between a case where the object thatis the recognition target of the surrounding environment recognitionsensors 3 has a high strength and a case where the object has a lowstrength. The surrounding environment recognition sensors 3 detect thestrength of the recognition target by using the wavelength patterndifference. In a case where the radar constitutes the surroundingenvironment recognition sensors 3, the brightness and the color of therecognition target are detected by the difference between the wavelengthpatterns of the reflected waves of the radar. In a case where the cameraconstitutes the surrounding environment recognition sensors 3, thebrightness and the color of the recognition target are detected by animage contrast difference.

In this embodiment, the plurality of surrounding environment recognitionsensors 3 are mounted on the vehicle. For example, as illustrated inFIG. 2 , a sensor 1 (3 a) as a first sensor and a sensor 2 (3 b) as asecond sensor constitute the surrounding environment recognition sensors3. According to FIG. 2 , the subject vehicle has the sensor 1 on a rightfront lateral side mounting position of the subject vehicle and has thesensor 2 on a right rear lateral side mounting position of the subjectvehicle. Herein, the sensor 1 and the sensor 2 detect the situations ofdifferent detection areas. For example, as illustrated in FIG. 2 , thesensor 1 detects the situation of a first area on a right front side ofthe subject vehicle and the sensor 2 detects the situation of a secondarea on a right rear side of the subject vehicle, which is an areadifferent from the first area. As illustrated in FIG. 2 , the first areaand the second area do not constitute a detection area that fully coversthe right side of the subject vehicle, and thus the blind spot area ispresent between the first area and the second area. In this embodiment,the blind spot area is an area surrounding a lateral side of the subjectvehicle and is an area other than the first area and the second area. Inother words, the blind spot area means an area where the sensor 1 cannotdetect, in the first area, the position information of thetracking-target moving body that is present around the subject vehicleand the sensor 2 cannot detect, in the second area, the positioninformation of the tracking-target moving body that is present aroundthe subject vehicle, and a surrounding area within a predetermined rangefrom the vehicle. In the example of FIG. 2 , the blind spot area isillustrated as an area that connects the mounting position of the sensor1, the mounting position of the sensor 2, and the intersection where theboundary line of the first area and the boundary line of the second areaintersect with each other. More specifically, in the example of FIG. 2 ,the second area is set to overlap part of the first area, and thus theblind spot area is an area that connects the mounting position of thesensor 1, the mounting position of the sensor 2, and the intersectionwhere the boundary line of the first area and the boundary line of thesecond area intersect with each other and an area where the first areaand the second area do not overlap each other.

The number of the surrounding environment recognition sensors 3 that aremounted on the vehicle is not limited to two as in the example of FIG. 2. Two or more sensors may be mounted on the vehicle. For example,although only two sensors, one being the sensor 1 and the other beingthe sensor 2, are provided on the right side of the subject vehicle inthe example of FIG. 2 , sensors may be provided on the left side of thesubject vehicle as well. For example, although not illustrated herein, asensor 3 may be provided on a left front lateral side mounting positionof the subject vehicle and a sensor 4 may be provided on a left rearlateral side mounting position of the subject vehicle. In a case wherethe sensor 3 and the sensor 4 are provided on the left side of thesubject vehicle, the sensor 3 detects the situation of a third area on aleft front side of the subject vehicle and the sensor 4 detects thesituation of a fourth area on a left rear side of the subject vehicle,which is an area different from the third area. In this case, the firstsensor may be the sensor 3 and the second sensor may be the sensor 4.However, in the description of the following example, the first sensorwill be described as the sensor 1 and the second sensor will bedescribed as the sensor 2 for convenience of description.

Referring back to FIG. 1 , the basic function of the navigation system 4is to guide the subject vehicle to a predetermined destination. Thenavigation system 4 is provided at least with a GPS sensor 4 a that isused to detect the current position of the subject vehicle by electricnavigation, a map database 4 b that stores map information required forthe traveling of the vehicle, and a computation processing device thatcomputes information on a path from the subject vehicle to apredetermined destination. In this embodiment, the navigation system 4outputs, to the ECU 1, various types of information obtained by the GPSsensor 4 a, the map database 4 b, the computation processing device, andthe like. In this embodiment, examples of the various types ofinformation transmitted from the navigation system 4 to the ECU 1include information on the position of the subject vehicle, informationon the position of the intersection, and information on the path fromthe subject vehicle to the predetermined destination. However, thevarious types of information transmitted from the navigation system 4 tothe ECU 1 are not limited thereto.

The humidity sensor 5 is a humidity detection device that detectshumidity around the subject vehicle. The humidity sensor 5 outputs, tothe ECU 1, a signal that shows the level of the detected humidity. Thewiper sensor 6 is a wiper operation speed detection device that detectsthe operation speed of a wiper which is mounted on the front window ofthe subject vehicle or the like. The wiper sensor 6 outputs, to the ECU1, a signal that shows the detected wiper operation speed. The ECU 1estimates the rainfall around the subject vehicle based on the signalthat is input from the wiper sensor 6. The ECU 1 estimates that therainfall around the subject vehicle is large when the wiper operationspeed is high and estimates that the rainfall around the subject vehicleis small when the wiper operation speed is low.

The actuator 7 is a brake actuator, accelerator actuator, and steeringactuator that intervenes in a driver's driving operation and drives thebrake, accelerator, and steering of the subject vehicle based on adriving support signal from the ECU 1. The display 8, which is a displaydevice that is disposed in the vehicle, displays various types ofinformation and provides a warning or notification for the driver inaccordance with the driving support signal output from the ECU 1. Thespeaker 9 provides a warning or notification for the driver byoutputting a predetermined sound in accordance with the driving supportsignal from the ECU 1. In this manner, the display 8 and the speaker 9perform screen display and sound output as a human-machine interface(HMI) such as a head-up display (HUD).

According to FIG. 1 , the ECU 1 is provided at least with a positiondetection unit 1 a, a position estimation unit 1 b, a trajectorycalculation unit 1 c, a support execution unit 1 d, and an estimationaccuracy setting unit 1 e.

The position detection unit 1 a of the ECU 1 is a position detectionunit that detects the position of the tracking-target moving body whichmoves in the first area covered by the first sensor and the second areacovered by the second sensor. Specifically, the position detection unit1 a detects the position of the tracking-target moving body that movesin the first area and the second area based on the surroundingenvironment information input from the surrounding environmentrecognition sensors 3. In addition, the position detection unit 1 afunctions to detect the speed and the acceleration and deceleration ofthe tracking-target moving body that moves in the first area and thesecond area based on the surrounding environment information input fromthe surrounding environment recognition sensors 3.

The position estimation unit 1 b of the ECU 1 is a position estimationunit that estimates the position of the tracking-target moving bodywhich moves in the blind spot area, which is a surrounding area on alateral side of the subject vehicle and is an area other than the firstarea and the second area, based on the position of the tracking-targetmoving body detected in at least one of the first area and the secondarea by the position detection unit 1 a. Specifically, the positionestimation unit 1 b estimates the position of the tracking-target movingbody that moves into the blind spot area from within the first areabased on the surrounding environment information detected in the firstarea and input by the surrounding environment recognition sensors 3immediately before the tracking-target moving body enters the blind spotarea. Alternatively, the position estimation unit 1 b estimates thespeed and the acceleration of the tracking-target moving body that movesinto the blind spot area from within the second area based on thesurrounding environment information detected in the second area andinput by the surrounding environment recognition sensors 3 immediatelybefore the tracking-target moving body enters the blind spot area.

The trajectory calculation unit 1 c of the ECU 1 is a trajectorycalculation unit that calculates the trajectory of the tracking-targetmoving body, so that the trajectory of the moving body detected in thefirst area and the second area and the trajectory of the moving bodyestimated in the blind spot area are continuous to each other, byestimating the position of the moving body by controlling the positionestimation unit 1 b when the tracking-target moving body leaves one ofthe first area and the second area and enters the blind spot area and bydetecting the position of the moving body by controlling the positiondetection unit 1 a when the moving body leaves the blind spot area andenters the other one of the first area and the second area. In otherwords, the trajectory calculation unit 1 c calculates the trajectory ofthe tracking-target moving body, so that the trajectory of the movingbody detected in the first area and the second area and the trajectoryof the moving body estimated in the blind spot area are continuous toeach other, by estimating the position of the moving body by controllingthe position estimation unit 1 b when the tracking-target moving bodyleaves the first area to enter the blind spot area or thetracking-target moving body leaves the second area to enter the blindspot area and by detecting the position of the moving body bycontrolling the position detection unit 1 a when the moving body leavesthe blind spot area to enter the second area after leaving the firstarea and entering the blind spot area or the moving body leaves theblind spot area to enter the first area after leaving the second areaand entering the blind spot area. In this embodiment, thetracking-target moving body that is tracked by the trajectorycalculation unit 1 c is a moving body which enters the first areathrough the blind spot area from the second area or a moving body whichenters the second area through the blind spot area from the first area.

The processing for switching between the control by the positionestimation unit 1 b and the control by the position detection unit 1 athat is executed by the trajectory calculation unit 1 c will bedescribed in detail with reference to FIG. 3 . In FIG. 3 , a followingvehicle is illustrated as an example of the tracking-target moving body,the following vehicle moving into the first area covered by the sensor 1as the first sensor on the right front side of the subject vehicle froma position in the second area covered by the sensor 2 as the secondsensor on the right rear side of the subject vehicle through the blindspot area on a right side of the subject vehicle. In FIG. 3 , the centerof the subject vehicle is a starting point, the traveling direction ofthe subject vehicle is the X axis, and the direction perpendicular tothe traveling direction of the subject vehicle is the Y axis. Inaddition, in FIG. 3 , an estimation area is set in advance to includethe blind spot area on the right side of the subject vehicle. Theestimation area is a rectangular area in which the line connecting themounting position of the sensor 1 to the mounting position of the sensor2 and parallel to the X axis is the short side and the respective linesparallel to the Y axis from the mounting position of the sensor 1 andthe mounting position of the sensor 2 and extended for the blind spotarea to be included are the long sides. In this embodiment, the upperlong side of the estimation area corresponds to a blind spot exit lineand the lower long side of the estimation area corresponds to a blindspot entrance line. In FIG. 3 , a blind spot entrance confirmation areais set in advance within a predetermined range on a side nearer (thatis, the rear side of the subject vehicle) than the blind spot entranceline on the lower side of the estimation area. The blind spot entranceconfirmation area is an area that is used to confirm that thetracking-target moving body enters the blind spot area for the subjectvehicle.

In the situation illustrated in FIG. 3 , the trajectory calculation unit1 c detects the position (x₁, y₁) of the following vehicle as thetracking-target moving body in the second area covered by the secondsensor by controlling the position detection unit 1 a and also detectsthe speed (Vx₁, Vy₁) of the moving body. Then, the trajectorycalculation unit 1 c determines whether the tracking-target moving bodyenters the blind spot area based on the position (x₁, y₁) of the movingbody detected by the position detection unit 1 a and the speed (Vx₁,Vy₁) of the moving body. For example, in a case where a determinationthreshold ΔT(s) is set as the length of time required for thetracking-target moving body to move the distance corresponding to theheight of the blind spot entrance confirmation area (that is, the shortside of the rectangle) and the distance from the position (x₁, y₁) ofthe moving body to the blind spot entrance line is a distance L1, thetrajectory calculation unit 1 c calculates the length of time t(s)required for the moving body to move to the blind spot entrance linefrom the position (x₁, y₁) of the moving body as “t(s)=L1/(Vx₁, Vy₁)”.Then, the trajectory calculation unit 1 c determines that thetracking-target moving body enters the blind spot area for the subjectvehicle in a case where the time t(s) required for the moving body tomove to the blind spot entrance line satisfies the condition of“t(s)<ΔT(s)”.

The trajectory calculation unit 1 c executes the following processing ina case where the following vehicle as the tracking-target moving body isdetermined to enter the blind spot area for the subject vehicle. Whenthe position (x₀, y₀) and the speed (Vx₀, Vy₀) of the moving body aredetected by the position detection unit 1 a on the blind spot entranceline that corresponds to the lower side of the estimation area in thesecond area covered by the second sensor, the trajectory calculationunit 1 c switches from the control by the position detection unit 1 a tothe control by the position estimation unit 1 b and estimates theposition (x′, y′) and the speed (V′x, V′y) of the moving body moving inthe estimation area including the blind spot area. For example, thetrajectory calculation unit 1 c controls the position estimation unit 1b, and calculates the x coordinate showing the position of the movingbody moving in the estimation area as “x′=x₀+(Vx₀)×estimated elapsedtime” and calculates the y coordinate showing the position of the movingbody moving in the estimation area as “y′=y₀+(Vy₀)×estimated elapsedtime”. Herein, the estimated elapsed time means the elapsed time thatbegins to be counted when the moving body passes through the blind spotentrance line. In addition, the trajectory calculation unit 1 c controlsthe position estimation unit 1 b, and calculates the speed of the movingbody moving in the estimation area as “(V′x, V′y)=(Vx₀, Vy₀)” on theassumption that the moving body moves in the estimation area in a statewhere the speed (Vx₀, Vy₀) detected on the blind spot entrance line bythe position detection unit 1 a is maintained. Then, the trajectorycalculation unit 1 c switches from the control by the positionestimation unit 1 b to the control by the position detection unit 1 awhen the position (x₂, y₂) and the speed (Vx₂, Vy₂) of the moving bodyare detected by the position detection unit 1 a on the blind spot exitline corresponding to the upper side of the estimation area in the firstarea covered by the first sensor.

The trajectory calculation unit 1 c calculates the trajectory of thetracking-target moving body based on the position of the followingvehicle as the tracking-target moving body that is obtained in thismanner. Specifically, as illustrated in FIG. 3 , the trajectorycalculation unit 1 c calculates the trajectory of the following vehicleas the tracking-target moving body based on the position of the movingbody detected to the blind spot entrance line in the second area coveredby the second sensor by the position detection unit 1 a, the position ofthe moving body estimated in the estimation area by the positionestimation unit 1 b, and the position of the moving body detected fromthe blind spot exit line in the first area covered by the first sensorby the position detection unit 1 a.

In the example described with reference to FIG. 3 , the estimation areais set in advance for the blind spot area to be included. However, theestimation area may not be set. In this case, the boundary lines of thearea detected by the surrounding environment recognition sensors 3 maybe set as the blind spot entrance line and the blind spot exit line. Forexample, although not illustrated herein, the boundary line of thesecond area on the blind spot area side may be set as the blind spotentrance line and the boundary line of the first area on the blind spotarea side may be set as the blind spot exit line.

Referring back to FIG. 1 , the support execution unit 1 d of the ECU 1is a support execution unit that executes the driving support based onthe trajectory of the tracking-target moving body which is tracked bythe trajectory calculation unit 1 c. For example, the support executionunit 1 d executes the driving support for avoiding a collision betweenthe subject vehicle and the tracking-target moving body by using varioustypes of information (for example, acceleration, yaw rate, and vehiclespeed of the subject vehicle) showing the vehicle momentum of thesubject vehicle input from the vehicle momentum detection sensors 2,information on the position of the subject vehicle input from thenavigation system 4, the trajectory of the tracking-target moving bodytracked by the trajectory calculation unit 1 c, and the like. Examplesof the driving support that is executed by the support execution unit 1d include driving support by executing vehicle control, driving supportby providing warning, and driving support by providing notification. Thedriving support by executing vehicle control is support for controllingthe behavior of the vehicle via the actuator 7 so as to avoid acollision between the subject vehicle and the tracking-target movingbody in cases such as immediately before the occurrence of the collisionbetween the subject vehicle and the tracking-target moving body. Thedriving support by providing warning is support for providing a warningfor the driver of the subject vehicle via the display 8 and/or thespeaker 9 so that a driving operation for avoiding a collision isperformed in a case where, for example, the collision between thesubject vehicle and the tracking-target moving body is predicted tooccur. The driving support by providing notification is support forproviding a notification for the driver via the display 8 and/or thespeaker 9 so that the driver can recognize the presence of the movingbody in a case where, for example, the moving body is present at aposition where a collision between the subject vehicle and thetracking-target moving body is likely to occur in the future.

According to the driving support apparatus of this embodiment asdescribed above, the driving support can be continuously executed, evenin a case where another moving body traveling in parallel to the vehicleby the vehicle moves into the blind spot area between the plurality ofsensors during the execution of the driving support for thetracking-target moving body, based on the trajectory of the moving bodytracked by checking the position of the moving body moving in the blindspot area.

It is desirable that the content of the support for the driving supportthat is executed by the support execution unit 1 d is content of thesupport in accordance with the tracking accuracy for the trajectory ofthe tracking-target moving body that is tracked by the trajectorycalculation unit 1 c. This is because a relatively high level ofaccuracy is required for the execution of the driving support byexecuting vehicle control and it is not desirable to execute the drivingsupport by executing vehicle control at a medium or low level ofaccuracy. Herein, the tracking accuracy for the trajectory of thetracking-target moving body is determined by the estimation accuracy ofthe position of the tracking-target moving body that is estimated by theposition estimation unit 1 b in the blind spot area. This is because arelatively unstable result may be obtained for the position of thetracking-target moving body that is estimated by the position estimationunit 1 b in the blind spot area although a relatively stable result maybe obtained for the position of the tracking-target moving body that isdetected by the position detection unit 1 a in the areas detected by thesurrounding environment recognition sensors 3. According to the relatedart, the execution of the driving support is halted at a moment when thetracking-target moving body enters the blind spot area. In the drivingsupport apparatus according to this embodiment, however, the drivingsupport continues, with the position of the moving body estimated andthe trajectory calculated, even if the tracking-target moving bodyenters the blind spot area. In addition, in the driving supportapparatus according to this embodiment, the content of the supportingfor the driving support is changed in accordance with the trackingaccuracy for the trajectory of the tracking-target moving body becauseit is desirable to continue the execution of the driving support withthe content in accordance with the tracking accuracy for the trajectoryof the tracking-target moving body during the continuation of theexecution of the driving support without halting execution of thedriving support in the blind spot area.

Specifically, in this embodiment, the support execution unit 1 d changesthe content of the support for the driving support in accordance withthe estimation accuracy of the position of the tracking-target movingbody that is estimated by the position estimation unit 1 b. For example,the support execution unit 1 d executes the driving support by executingvehicle control in a case where the estimation accuracy is high,executes the driving support by providing warning in a case where theestimation accuracy is medium, and executes the driving support byproviding notification in a case where the estimation accuracy is low.In a case where the estimation accuracy is high, the support executionunit 1 d may execute the driving support by providing warning and thedriving support by providing notification along with the driving supportby executing vehicle control. In a case where the estimation accuracy ismedium, the support execution unit 1 d may execute the driving supportby providing notification along with the driving support by providingwarning. In a case where the estimation accuracy is low, it is desirablethat the support execution unit 1 d executes only the driving support byproviding notification. In the driving support apparatus according tothis embodiment as described above, the degree of reliability (forexample, high, medium, and low) that relates to the estimation accuracyof the position of the tracking-target moving body in the blind spotarea is predicted in accordance with traveling situations and thepredicted estimation accuracy is transferred in advance to the supportexecution unit 1 d before the execution of the driving support.Accordingly, appropriate content of the support is determined andexecuted by the support execution unit 1 d.

The estimation accuracy setting unit 1 e of the ECU 1 is an estimationaccuracy setting unit that sets the estimation accuracy of the positionof the tracking-target moving body which is estimated by the positionestimation unit 1 b. Hereinafter, an example of the estimation accuracyset by the estimation accuracy setting unit 1 e will be described.

In this embodiment, the estimation accuracy setting unit 1 e may set theestimation accuracy to decrease as the relative speed between thesubject vehicle and the tracking-target moving body decreases and mayset the estimation accuracy to increase as the relative speed increases.For example, in a case where the following vehicle as an approachingtracking-target moving body approaches the blind spot entrance line ofthe estimation area including the blind spot area for the subjectvehicle to pass by the subject vehicle on a right rear side of thesubject vehicle as illustrated in FIG. 4 , the estimation accuracysetting unit 1 e calculates the speed that is obtained by subtractingthe speed V1(0) of the subject vehicle from the speed V2(0) of themoving body as the relative speed “ΔV(0)=V2(0)−V1(0)”. The speed of themoving body is detected based on the surrounding environment informationrelating to the tracking-target moving body that is input from thesurrounding environment recognition sensors 3 and the speed of thesubject vehicle is detected based on the signal that is input from thevehicle speed sensor 2 c. Then, the estimation accuracy setting unit 1 ecalculates the estimation accuracy by using the arithmetic expression of“estimation accuracy=K×L2/ΔV(0)”. Herein, K is a design parameter, L2 isthe length (m) of the estimation area, and ΔV(0) is the relative speed.If the estimation accuracy is calculated based on this arithmeticexpression, the estimation accuracy is set to decrease as ΔV(0)decreases as illustrated in FIG. 5 . This is because the length of timeduring which the tracking-target moving body is positioned in theestimation area including the blind spot area increases as the relativespeed ΔV(0) decreases and the trajectory of the moving body becomes morelikely to change over time. Also, as illustrated in FIG. 5 , theestimation accuracy is set to increase as the relative speed ΔV(0)increases. This is because the length of time during which thetracking-target moving body is positioned in the estimation areaincluding the blind spot area decreases as the relative speed ΔV(0)increases and the trajectory of the moving body becomes less likely tochange over time.

In addition, the estimation accuracy setting unit 1 e may set theestimation accuracy in accordance with the attribute of thetracking-target moving body. For example, in a case where the followingvehicle as an approaching tracking-target moving body is present in thesecond area covered by the second sensor to pass by the subject vehicleon a right rear side of the subject vehicle as illustrated in FIG. 3above, the estimation accuracy setting unit 1 e determines the attributeof the tracking-target moving body based on the information that relatesto the attribute of the surrounding obstacle such as the strength,brightness, and color of the recognition target included in thesurrounding environment information input from the second sensor.Examples of the attribute of the tracking-target moving body include apedestrian, a bicycle, a motorcycle, and a car. In a case where theradar constitutes the surrounding environment recognition sensors 3, theattribute can be determined based on, for example, the strength of thewaves reflected to the radar from the object. In a case where the cameraconstitutes the surrounding environment recognition sensors 3, theattribute can be determined based on, for example, pattern recognition.In a case where the attribute of the tracking-target moving body is thepedestrian as illustrated in FIG. 6 , the estimation accuracy settingunit 1 e sets the estimation accuracy to be lower than the estimationaccuracy for any other attribute. In a case where the attribute of thetracking-target moving body is the car, the estimation accuracy settingunit 1 e sets the estimation accuracy to be higher than the estimationaccuracy for any other attribute. This is because the trajectory of thepedestrian is considered to be more likely to change than the trajectoryof the car. Likewise, in a case where the attribute of thetracking-target moving body is the bicycle as illustrated in FIG. 6 ,the estimation accuracy setting unit 1 e sets the estimation accuracy tobe the second-lowest to follow the estimation accuracy for thepedestrian. In a case where the attribute of the tracking-target movingbody is the motorcycle, the estimation accuracy setting unit 1 e setsthe estimation accuracy to be the second-highest to follow theestimation accuracy for the car. This is because the trajectory of thebicycle is considered to be more likely to change than the trajectory ofthe motorcycle.

The estimation accuracy setting unit 1 e may set the estimation accuracyto increase as the acceleration and deceleration of the moving bodyother than the tracking-target moving body that is present around thesubject vehicle at which the moving body approaches the tracking-targetmoving body decreases and may set the estimation accuracy to decrease asthe acceleration and deceleration increases. For example, in a casewhere the moving body other than the following vehicle as thetracking-target moving body that approaches the subject vehicle on aright rear side of the subject vehicle to pass by the subject vehicle ispresent in front of the following vehicle and is decelerating toapproach the following vehicle as illustrated in FIG. 7 , the estimationaccuracy setting unit 1 e calculates the estimation accuracy inaccordance with the deceleration of the vehicle ahead as the moving bodyother than the following vehicle. The deceleration is detected based onthe surrounding environment information relating to the moving bodyother than the following vehicle input from the surrounding environmentrecognition sensors 3. Then, the estimation accuracy setting unit 1 ecalculates the estimation accuracy by using, for example, the arithmeticexpression of “estimation accuracy=K×A_(p)/T_(HeadWay)”. Herein, K is adesign parameter, A_(p) (m/s²) is the acceleration and deceleration ofthe moving body other than the following vehicle, and T_(HeadWay) (s) isthe inter-vehicular time from the subject vehicle to the moving bodyother than the following vehicle. In a case where the moving body otherthan the following vehicle stops, A_(p) is equal to ∞. If the estimationaccuracy is calculated based on this arithmetic expression, theestimation accuracy is set to decrease as the acceleration anddeceleration increases as illustrated in FIG. 8 . This is because theinter-vehicle distance becomes more likely to be adjusted and thetrajectory becomes more likely to be changed through speed adjustment asthe acceleration and deceleration increases so that the tracking-targetmoving body and the moving body other than the following vehicle do notcollide with each other in the estimation area including the blind spotarea. Also, the estimation accuracy is set to increase as theacceleration and deceleration decreases as illustrated in FIG. 8 . Thisis because the likelihood of the inter-vehicle distance adjustmentthrough speed adjustment and the likelihood of the trajectory change,the inter-vehicle distance adjustment and the trajectory change are forthe tracking-target moving body and the moving body other than thefollowing vehicle not to collide with each other in the estimation areaincluding the blind spot area, decrease as the acceleration anddeceleration decreases. In the example of FIG. 7 according to thisembodiment, the deceleration of the vehicle ahead is described, as anexample of the moving body other than the following vehicle as thetracking-target moving body. However, the invention is not limitedthereto. Although not illustrated, in a case where, for example, avehicle behind that is present further behind the following vehicle asthe moving body is the moving body other than the following vehicle thatis a tracking target, the estimation accuracy setting unit 1 e may setthe estimation accuracy as described above in accordance with theacceleration of the vehicle behind.

The estimation accuracy setting unit 1 e may set the estimation accuracyto increase as the distance from the subject vehicle to the intersectionincreases and may set the estimation accuracy to decrease as thedistance decreases. The distance to the intersection is detected basedon the information on the position of the subject vehicle input from theGPS sensor 4 a of the navigation system 4 and the information on theposition of the intersection input from the map database 4 b. Forexample, assuming a case where the subject vehicle moves into thevicinity of the intersection as illustrated in FIG. 9 , theparallel-traveling vehicle as the tracking-target moving body moving inthe blind spot area for the subject vehicle is likely to turn rightalong the road structure at the intersection and the pedestrian as thetracking-target moving body moving in the blind spot area for thesubject vehicle is likely to turn to the right along the sidewalk at theintersection. As described above, the tracking-target moving body islikely to change the trajectory by, for example, turning right or leftwhile moving, without moving and traveling in parallel to the subjectvehicle, at the intersection even in a case where the subject vehicletravels straight. As illustrated in FIG. 9 , a predetermined distance L4is set as a threshold for determining whether the distance to theintersection is long or short and the estimation accuracy setting unit 1e determines that the distance to the intersection is short in a casewhere the distance from the subject vehicle to the intersection isshorter than the predetermined distance L4 and determines that thedistance to the intersection is long in a case where the distance fromthe subject vehicle to the intersection is longer than the predetermineddistance L4. If the distance to the intersection is determined in thismanner, the estimation accuracy is set to decrease as the distance tothe intersection decreases as illustrated in FIG. 10 . This is becausethe tracking-target moving body becomes more likely to change thetrajectory by moving along the road structure at the intersection in theestimation area including the blind spot area as the distance to theintersection decreases. Also, the estimation accuracy is set to increaseas the distance to the intersection increases as illustrated in FIG. 10. This is because the likelihood of the trajectory change by thetracking-target moving body based on the movement along the roadstructure at the intersection in the estimation area including the blindspot area decreases as the distance to the intersection increases.

The estimation accuracy setting unit 1 e may set the estimation accuracyto increase as the humidity around the subject vehicle decreases and mayset the estimation accuracy to decrease as the humidity increases. Thehumidity around the subject vehicle is detected based on the signalinput from the humidity sensor 5. For example, as illustrated in FIG. 11, the estimation accuracy is set to decrease as the humidity around thesubject vehicle increases. This is because the weather more affects thetracking-target moving body, the moving body becomes more likely to bespeed-adjusted, and the trajectory becomes more likely to be changed asthe humidity increases. Also, the estimation accuracy is set to increaseas the humidity around the subject vehicle decreases as illustrated inFIG. 11 . This is because the weather less affects the tracking-targetmoving body, the moving body becomes less likely to be speed-adjusted,and the trajectory becomes less likely to be changed as the humiditydecreases.

The estimation accuracy setting unit 1 e may set the estimation accuracyto increase as the rainfall around the subject vehicle decreases and mayset the estimation accuracy to decrease as the rainfall increases. Therainfall around the subject vehicle is detected, based on the signalthat shows the wiper operation speed which is input from the wipersensor 6, to be large at a high operation speed and to be small at a lowoperation speed. For example, the estimation accuracy is set to decreaseas the wiper operation speed around the subject vehicle increases asillustrated in FIG. 12 . This is because a large-rainfall situation isassumed at a high wiper operation speed and the weather more affects thetracking-target moving body, the moving body becomes more likely to bespeed-adjusted, and the trajectory becomes more likely to be changed inthis large-rainfall situation. Also, the estimation accuracy is set toincrease as the wiper operation speed decreases as illustrated in FIG.12 . This is because a small-rainfall situation is assumed at a lowwiper speed and the weather less affects the tracking-target movingbody, the moving body becomes less likely to be speed-adjusted, and thetrajectory becomes less likely to be changed in this small-rainfallsituation.

According to the driving support apparatus of this embodiment, thetracking accuracy for the trajectory of the tracking-target moving bodycan be appropriately set in various situations as described above.Accordingly, the execution of the driving support can continue withoutstopping in the blind spot area, and the driving support can continuewith appropriate content of the support in accordance with the trackingaccuracy for the trajectory of the tracking-target moving body.

Next, various types of processing that are executed by the drivingsupport apparatus described above will be described with reference toFIGS. 13 and 14 . FIG. 13 is a flowchart illustrating an example of thebasic processing that is executed by the driving support apparatusaccording to the invention. FIG. 14 is a flowchart illustrating examplesof estimation accuracy setting processing and driving support changeprocessing that are executed by the driving support apparatus accordingto the invention. In this embodiment, the various types processing thatare illustrated in FIGS. 13 and 14 are repeatedly executed in shortcomputation periods.

As illustrated in FIG. 13 , the ECU 1 acquires the surroundingenvironment information from the areas detected by the surroundingenvironment recognition sensors 3 (Step S10). In Step S10, the ECU 1acquires, for example, the surrounding environment information relatingto the following vehicle as the tracking-target moving body moving inthe second area covered by the sensor 2 as the second sensor asillustrated in FIG. 3 above.

The ECU 1 determines whether or not the tracking-target moving bodyenters the blind spot area (Step S11) based on the surroundingenvironment information that is acquired in Step S10. In Step S11, theECU 1 determines that the tracking-target moving body enters the blindspot area for the subject vehicle in a case where, for example, the timet(s) required for the moving body to move to the blind spot entranceline satisfies the condition of “t(s)<ΔT(s)” as illustrated in FIG. 3above. In a case where the time t(s) required for the moving body tomove to the blind spot entrance line does not satisfy the condition of“t(s)<ΔT(s)”, the ECU 1 determines that the tracking-target moving bodydoes not enter the blind spot area for the subject vehicle.

In a case where it is determined in Step S11 that the tracking-targetmoving body enters the blind spot area (Step S11: Yes), the ECU 1 allowsthe processing to proceed to Step S12. In a case where it is determinedin Step S11 that the tracking-target moving body does not enter theblind spot area (Step S11: No), the ECU 1 allows the processing toproceed to Step S13.

The ECU 1 estimates the position of the moving body moving in the blindspot area (Step S12) based on the surrounding environment informationthat is acquired in Step S10. If, for example, the position (x₀, y₀) andthe speed (Vx₀, Vy₀) of the moving body are detected in Step S12 on theblind spot entrance line corresponding to the lower side of theestimation area in the second area covered by the second sensor asillustrated in FIG. 3 above, the ECU 1 estimates the position (x′, y′)and the speed (V′x, V′y) of the moving body moving in the estimationarea including the blind spot area. For example, the ECU 1 calculatesthe x coordinate showing the position of the moving body moving in theestimation area as “x′=x₀+(Vx₀)×estimated elapsed time” and calculatesthe y coordinate showing the position of the moving body moving in theestimation area as “y′=y₀+(Vy₀)×estimated elapsed time”. In addition,the ECU 1 calculates the speed of the moving body moving in theestimation area as “(V′x, V′y)=(Vx₀, Vy₀)” on the assumption that themoving body moves in the estimation area in a state where the speed(Vx₀, Vy₀) detected on the blind spot entrance line is maintained.

With the position estimation processing performed in Step S12 in thecase of a Yes determination in Step S11, the ECU 1 calculates thetrajectory of the moving body (Step S13) based on the position of thetracking-target moving body that is detected from the surroundingenvironment information acquired in Step S10 (for example, the positionof the moving body moving in the second area covered by the secondsensor) and the position of the tracking-target moving body that isestimated in Step S12 (for example, the position of the moving bodymoving in the estimation area including the blind spot area). With theposition estimation processing not performed in Step S12 in the case ofa No determination in Step S11, the ECU 1 calculates the trajectory ofthe moving body in Step S13 based on the position of the tracking-targetmoving body that is detected from the surrounding environmentinformation acquired in Step S10 (for example, the position of themoving body moving in the second area covered by the second sensor).

The ECU 1 determines whether or not the driving support needs to beexecuted for the subject vehicle (Step S14) based on the trajectory ofthe moving body that is tracked in Step S13. In Step S14, the ECU 1computes the likelihood of a collision between the subject vehicle andthe moving body by, for example, using the trajectory of the moving bodythat is tracked in Step S13 and determines that the driving supportneeds to be executed in a case where the collision is found to be likelyas a result of the computation. In Step S14, the ECU 1 determines thatthe driving support does not have to be executed in a case where thecollision is found to be unlikely as a result of the computation, andreturns this processing. Then, the processing in FIG. 13 is repeatedlyexecuted.

In a case where it is determined in Step S14 that the driving supportneeds to be executed for the subject vehicle (Step S14: Yes), the ECU 1executes the driving support in accordance with the likelihood of thecollision (Step S15). In Step S15, the ECU 1 executes, for example, thesupport for controlling the behavior of the vehicle, as the drivingsupport by executing vehicle control, via the actuator 7 so as to avoidthe collision between the subject vehicle and the tracking-target movingbody. In addition, in Step S15, the ECU 1 may execute the drivingsupport by providing warning and the driving support by providingnotification in addition to the driving support by executing vehiclecontrol. After the processing of Step S15, this processing isterminated. Then, the processing in FIG. 13 is repeatedly executed.

In a case where the processing in FIG. 13 is repeatedly executed, theECU 1 executes, for example, the following processing in Step S13described above. As an example, a case where the position estimationprocessing is performed in Step S12 in the case of a Yes determinationin Step S11 of the previous processing and then the processing in FIG.13 is executed again and a No determination is made in Step S11 of thecurrent processing will be described. In this case, the ECU 1 calculatesthe trajectory of the tracking-target moving body based on the positionof the tracking-target moving body that is detected from the surroundingenvironment information acquired in Step S10 of the previous processing(for example, the position of the moving body moving in the second areacovered by the second sensor), the position of the tracking-targetmoving body that is estimated in Step S12 of the previous processing(for example, the position of the moving body moving in the estimationarea including the blind spot area), and the position of thetracking-target moving body that is detected from the surroundingenvironment information acquired in Step S10 of the current processing(for example, the position of the moving body moving in the first areacovered by the first sensor).

In addition, in the driving support apparatus according to thisembodiment, the estimation accuracy setting processing and the drivingsupport change processing that are illustrated in FIG. 14 to bedescribed below are executed in conjunction with the basic processingthat is illustrated in FIG. 13 described above.

As illustrated in FIG. 14 , the ECU 1 determines (Step S20) whether theposition of the moving body moving in the blind spot area has beenestimated, that is, whether or not the position estimation processingcorresponding to the processing of Step S12 in FIG. 13 described abovehas been performed. In a case where it is determined in Step S20 thatthe estimation of the position of the moving body has not been performed(Step S20: No), the ECU 1 returns this processing. Then, the processingin FIG. 14 is repeatedly executed.

In a case where it is determined in Step S20 that the estimation of theposition of the moving body has been performed (Step S20: Yes), the ECU1 sets the estimation accuracy (Step S21) by using at least one of themethods illustrated in FIGS. 4 to 12 described above based on thesurrounding environment information acquired in Step S10 in FIG. 13 . InStep S21, the estimation accuracy is set to decrease as the relativespeed between the subject vehicle and the tracking-target moving bodydecreases and to increase as the relative speed increases. Herein, theestimation accuracy may be set in accordance with the attribute of thetracking-target moving body. In addition, the estimation accuracy may beset to increase as the acceleration and deceleration at which the movingbody other than the tracking-target moving body present around thesubject vehicle approaches the tracking-target moving body decreases andto decrease as the acceleration and deceleration increases. In addition,the estimation accuracy may be set to increase as the distance from thesubject vehicle to the intersection increases and to decrease as thedistance decreases. In addition, the estimation accuracy may be set toincrease as the humidity around the subject vehicle decreases and todecrease as the humidity increases. In addition, the estimation accuracymay be set to increase as the rainfall around the subject vehicledecreases and to decrease as the rainfall increases.

The ECU 1 changes the content of the support for the driving support(Step S22) in accordance with the estimation accuracy that is set inStep S21. For example, in Step S22, the ECU 1 changes the content of thesupport to execute the driving support by executing vehicle control in acase where the estimation accuracy is high, execute the driving supportby providing warning in a case where the estimation accuracy is medium,and execute the driving support by providing notification in a casewhere the estimation accuracy is low. The content of the support for thedriving support changed in Step S22 is executed in the processing ofStep S15 illustrated in FIG. 13 described above. After the processing ofStep S22, this processing is returned. Then, the processing in FIG. 14is repeatedly executed.

The invention claimed is:
 1. A driving support apparatus provided on asubject vehicle, the driving support apparatus comprising: processingcircuitry configured to: calculate a trajectory of a tracking-targetmoving body, so that a trajectory of the tracking-target moving bodydetected in at least one of a first area and a second area and atrajectory of the tracking-target moving body estimated in a blind spotarea are continuous to each other, by estimating a position of thetracking-target moving body when the tracking-target moving body leavesone of the first area and the second area and enters the blind spot areaand by detecting the position of the tracking-target moving body whenthe tracking-target moving body leaves the blind spot area and entersthe other one of the first area and the second area, determine that thetracking-target moving body leaves the second area and enters the blindspot area using a blind spot entrance confirmation area, the blind spotentrance confirmation area being set in advance, being set to have apredetermined range, being situated on a rear side of the subjectvehicle with respect to the blind spot area, and having boundaries thatare different from boundaries of the second area, and execute drivingsupport based on the calculated trajectory of the tracking-target movingbody.
 2. The driving support apparatus according to claim 1, furthercomprising: position detection circuitry configured to detect a positionof the tracking-target moving body moving in the first area and thesecond area, the first area being located on a front side of the subjectvehicle, the second area being located on the rear side of the subjectvehicle, wherein the processing circuitry is further configured toestimate the position of the tracking-target moving body moving in theblind spot area based on the position of the tracking-target moving bodydetected in any one of the first area and the second area by theposition detection circuitry, the blind spot area being an area otherthan the first area and the second area.
 3. The driving supportapparatus according to claim 1, wherein the processing circuitry isconfigured to change a content of the support for the driving support inaccordance with an estimation accuracy of the position of thetracking-target moving body.
 4. The driving support apparatus accordingto claim 3, wherein the processing circuitry is configured to executethe driving support by executing vehicle control in a case where theestimation accuracy is higher than a case where the driving support isexecuted by providing notification.
 5. The driving support apparatusaccording to claim 3, wherein the estimation accuracy is set to decreaseas a relative speed between the subject vehicle and the tracking-targetmoving body decreases and to increase as the relative speed increases.6. The driving support apparatus according to claim 3, wherein theestimation accuracy is set in accordance with an attribute of thetracking-target moving body.
 7. The driving support apparatus accordingto claim 3, wherein the estimation accuracy is set to increase as anacceleration and deceleration of a moving body other than thetracking-target moving body present around the subject vehicle at whichthe moving body approaches the tracking-target moving body decreases andto decrease as the acceleration and deceleration increases.
 8. A drivingsupport method performed by a driving support apparatus provided on asubject vehicle, the method comprising: calculating a trajectory of atracking-target moving body, so that a trajectory of the tracking-targetmoving body detected in at least one of a first area and a second areaand a trajectory of the tracking-target moving body estimated in a blindspot area are continuous to each other, by estimating a position of thetracking-target moving body when the tracking-target moving body leavesone of the first area and the second area and enters the blind spot areaand by detecting the position of the tracking-target moving body whenthe tracking-target moving body leaves the blind spot area and entersthe other one of the first area and the second area; determining thatthe tracking-target moving body leaves the second area and enters theblind spot area using a blind spot entrance confirmation area, the blindspot entrance confirmation area being set in advance, being set to havea predetermined range, being situated on a rear side of the subjectvehicle with respect to the blind spot area, and having boundaries thatare different from boundaries of the second area; and executing drivingsupport based on the calculated trajectory of the tracking-target movingbody.
 9. The method according to claim 8, further comprising: detectinga position of the tracking-target moving body moving in the first areaand the second area, the first area being located on a front side of thesubject vehicle, the second area being located on the rear side of thesubject vehicle; and estimating the position of the tracking-targetmoving body moving in the blind spot area based on the position of thetracking-target moving body detected in any one of the first area andthe second area, the blind spot area being an area other than the firstarea and the second area.
 10. The method according to claim 8, furthercomprising changing a content of the support for the driving support inaccordance with an estimation accuracy of the position of thetracking-target moving body.
 11. The method according to claim 10,further comprising executing the driving support by executing vehiclecontrol in a case where the estimation accuracy is higher than a casewhere the driving support is executed by providing notification.
 12. Themethod according to claim 10, wherein the estimation accuracy is set todecrease as a relative speed between the subject vehicle and thetracking-target moving body decreases and to increase as the relativespeed increases.
 13. The method according to claim 10, wherein theestimation accuracy is set in accordance with an attribute of thetracking-target moving body.
 14. The method according to claim 10,wherein the estimation accuracy is set to increase as an accelerationand deceleration of a moving body other than the tracking-target movingbody present around the subject vehicle at which the moving bodyapproaches the tracking-target moving body decreases and to decrease asthe acceleration and deceleration increases.
 15. A non-transitorycomputer readable medium having instructions stored therein, which whenexecuted by a processor of a driving support apparatus provided on asubject vehicle cause the processor to execute a method comprising:calculating a trajectory of a tracking-target moving body, so that atrajectory of the tracking-target moving body detected in at least oneof a first area and a second area and a trajectory of thetracking-target moving body estimated in a blind spot area arecontinuous to each other, by estimating a position of thetracking-target moving body when the tracking-target moving body leavesone of the first area and the second area and enters the blind spot areaand by detecting the position of the tracking-target moving body whenthe tracking-target moving body leaves the blind spot area and entersthe other one of the first area and the second area; determining thatthe tracking-target moving body leaves the second area and enters theblind spot area using a blind spot entrance confirmation area, the blindspot entrance confirmation area being set in advance, being set to havea predetermined range, being situated on a rear side of the subjectvehicle with respect to the blind spot area, and having boundaries thatare different from boundaries of the second area; and executing drivingsupport based on the calculated trajectory of the tracking-target movingbody.
 16. The non-transitory computer readable medium according to claim15, further comprising: detecting a position of the tracking-targetmoving body moving in the first area and the second area, the first areabeing located on a front side of the subject vehicle, the second areabeing located on the rear side of the subject vehicle; and estimatingthe position of the tracking-target moving body moving in the blind spotarea based on the position of the tracking-target moving body detectedin any one of the first area and the second area, the blind spot areabeing an area other than the first area and the second area.
 17. Thenon-transitory computer readable medium according to claim 15, furthercomprising changing a content of the support for the driving support inaccordance with an estimation accuracy of the position of thetracking-target moving body.
 18. The non-transitory computer readablemedium according to claim 17, further comprising executing the drivingsupport by executing vehicle control in a case where the estimationaccuracy is higher than a case where the driving support is executed byproviding notification.
 19. The non-transitory computer readable mediumaccording to claim 17, wherein the estimation accuracy is set todecrease as a relative speed between the subject vehicle and thetracking-target moving body decreases and to increase as the relativespeed increases.
 20. The non-transitory computer readable mediumaccording to claim 17, wherein the estimation accuracy is set inaccordance with an attribute of the tracking-target moving body.